Synchronization unit for a positive dual clutch

ABSTRACT

A synchronization unit for a positive dual clutch. The synchronization unit has a sleeve carrier that is axially and rotationally fixed to an output shaft and a shifting sleeve that is rotationally fixed and axially displaceable relative to the sleeve carrier. The synchronization rings of a synchronization clutch on the sleeve carrier side and the sleeve carrier comprise axially interlocked circumferential segments.

The invention relates to a synchronization unit for a positive dualclutch, in particular for a gearwheel mechanism, having a sleeve carrierwhich is connected axially and fixedly to a working shaft so as torotate with it, and having a selector sleeve which is fixed rotationallyand can be displaced axially relative to the sleeve carrier, and havingtwo frictionally acting synchronizer clutches which are assigned toopposite axial sides of the sleeve carrier and in each case one clutchgear, each synchronizer clutch having a multiple disk assembly, andhaving a plurality of pressure pieces which are arranged distributedover the circumference of the sleeve carrier and are mounted in anaxially adjustable manner by way of the selector sleeve for loading oneor the other synchronizer clutch.

A synchronization unit of this type is known from DE 32 08 945 A1. Theknown synchronization unit is provided for a positive dual clutch of agearwheel mechanism which is used, in particular, in the automotivefield. The known synchronization unit has a working shaft which isdesigned as a gear mechanism shaft and on which the sleeve carrier isarranged in a rotationally and axially fixed manner. The sleeve carrieris surrounded in a rotationally fixed manner by a selector sleeve whichcan be moved axially relative to the sleeve carrier. In each case oneclutch gear which is fastened to a corresponding gearwheel of thegearwheel mechanism is provided on opposite axial sides of the sleevecarrier. The sleeve carrier is assigned two axially movably mountedsynchronizer rings of two synchronizer clutches which are arranged so asto lie opposite one another, which synchronizer rings can be displacedaxially by pressure pieces which are mounted on the sleeve carrier. Amultiple disk assembly is arranged between each synchronizer ring andthe adjacent clutch gear, which multiple disk assembly is pressedtogether by corresponding axial pressure loading of the respectivesynchronizer ring and can thus transmit a torque frictionally to theclutch gear. The movement of the pressure piece is carried out by axialdisplacement of the selector sleeve which can be moved via a manuallinkage or the like. After rotational speed equalization has beencarried out between synchronizer ring and associated clutch gear, theselector sleeve is displaced to such an extent that a positiverotational drive can be achieved between synchronizer ring and clutchgear. For this purpose, the selector sleeve is provided with an insideaxial toothing system. On the same pitch circle diameter, the clutchgear and the associated synchronizer ring have complementary externaltoothing systems which are likewise configured as axial toothingsystems. The construction and function of the synchronizer clutch forthe other axial side of the sleeve carrier correspond to the describedconstruction and the described function.

It is an object of the invention to provide a synchronization unit ofthe type mentioned at the outset, which synchronization unit has areduced axial overall length in comparison with the prior art.

This object is achieved by virtue of the fact that sleeve-carrier-sidesynchronizer rings of the synchronizer clutch and the sleeve carrierhave axially indented circumferential sections. As a result, thesynchronizer rings and the sleeve carrier engage axially into oneanother, the sleeve carrier and/or the synchronizer rings havingcomplementary axial cutouts and/or axial projections. As a result of thesolution according to the invention, the synchronizer rings and thesleeve carrier are nested axially inside one another, which results in areduced axial overall length for this functional unit, in relation to arotational axis of the working shaft. As a result, it is possible todesign the entire synchronization unit with a reduced axial overalllength. The solution according to the invention is suitable in aparticularly advantageous way for gearwheel mechanisms of machines or ofmotor vehicles such as passenger vehicles, trucks or commercialvehicles.

In one refinement of the invention, the sleeve carrier is provided witha plurality of axial cutouts which are arranged distributed over itscircumference and are open in an alternating manner toward opposite endsides of the sleeve carrier. The cutouts which are arranged offset withrespect to one another in the circumferential direction and are opentoward opposite end sides of the sleeve carrier serve to receive bothsynchronizer rings from the respective opposite axial end sides.

In a further refinement of the invention, each synchronizer ring isprovided with a number of external toothing sections which correspondsto the number of axial cutouts of an end side of the sleeve carrier,which toothing sections are fitted axially and radially into thecutouts. As a result of this refinement, the synchronizer ring does nothave to be provided with an external toothing system over its entirecircumference. Rather, it is sufficient to provide the axial externaltoothing system over a considerably reduced circumferential length whichis adapted to the circumferential length of the cutouts of the sleevecarrier. As a result, the production of the synchronizer rings issimplified and is inexpensive. Each synchronizer ring preferably has acarrier ring, from which the external toothing sections project radiallyto the outside and, in the mounted state, protrude into the cutouts ofthe sleeve carrier. The circumferential length of the external toothingsections is smaller than the circumferential extent of the correspondingaxial cutout of the sleeve carrier, in order to make a certain mobilityof the synchronizer ring possible in the circumferential directionrelative to the sleeve carrier.

Accordingly, the external toothing sections are advantageously arrangedin the associated cutouts with play in the circumferential direction.

In a further refinement of the invention, the selector sleeve has anaxial inner toothing system which is complementary with respect to theexternal toothing sections and is recessed in sections in the region ofthe external toothing sections of each synchronizer ring and at theradial level of the cutouts of the sleeve carrier. This refinement isnecessary, in order to avoid a positive connection to the synchronizerrings in a neutral position of the selector sleeve. The mobility of thesynchronizer rings would be impaired as a result.

In a further refinement of the invention, the recessed regions of theselector sleeve are provided from opposite end sides in a complementarymanner with respect to the cutouts of the sleeve carrier such that theyalternate and are distributed over the circumference. This ensures, inthe neutral position of the selector sleeve, that the selector sleeve isnot positively connected to either of the two synchronizer rings. Thesleeve carrier has its full axial length in the circumferentialdirection between the cutouts, which full axial length is providedcontinuously with an axial external toothing system.

In a further refinement of the invention, both the sleeve carrier andthe selector sleeve which is arranged on the sleeve carrier in arotationally fixed and axially movable manner have complementary axialtoothing sections which extend over the entire axial length of sleevecarrier and selector sleeve, the axial toothing sections being provided,as viewed in the circumferential direction, between the cutouts of thesleeve carrier and the recessed regions of the internal toothing systemof the selector sleeve. As a result, a great axial guide length betweensleeve carrier and selector sleeve can be achieved, as a result of whichtilting moments of the selector sleeve relative to the sleeve carrierare reduced.

In a further refinement of the invention, the pressure pieces arearranged axially adjacently to the cutouts for the toothing sections inthe sleeve carrier. As a result, the pressure pieces can act directlyaxially on the synchronizer rings.

In a further refinement of the invention, the pressure pieces compriseball elements which are loaded by compression spring and interact withan inside circumferential groove of the selector sleeve, in order toensure axial displaceability of the pressure pieces during an axialmovement of the selector sleeve. In the neutral position of the selectorsleeve and the pressure pieces, the inner circumferential groove of theselector sleeve and the ball elements of the pressure pieces engage intoone another and remain operatively connected to one another even duringthe synchronization operation. In the case of a further axialdisplacement of the selector sleeve, in order to achieve a positiveconnection between the corresponding clutch elements of the dual clutch,the circumferential groove and the ball elements of the pressure piecespass out of engagement with one another.

Further advantages and features of the invention result from the claimsand from the following description of one preferred exemplary embodimentof the invention which is shown by way of the drawings, in which:

FIG. 1 shows a perspective, cut-away illustration of one embodiment of asynchronization unit according to the invention for a positive dualclutch,

FIG. 2 shows the synchronization unit according to FIG. 1 from anotherperspective,

FIG. 3 shows the synchronization unit according to FIGS. 1 and 2 withthe omission of an outer selector sleeve,

FIG. 4 shows the synchronization unit according to FIGS. 1 to 3 with aselector sleeve which is displaced into a positive shifting position,

FIG. 5 shows the synchronization unit according to FIG. 4 with aselector sleeve which is situated in the neutral position,

FIG. 6 shows a sleeve carrier of the synchronization unit according toFIGS. 1 to 5,

FIG. 7 shows a synchronizer ring of the synchronization unit accordingto FIGS. 1 to 5,

FIG. 8 shows the selector sleeve for the synchronization unit accordingto FIGS. 1 to 5, and

FIG. 9 shows a greatly enlarged illustration of a detail of thesynchronization unit according to FIG. 3 without a selector sleeve.

A positive dual clutch, details of which can be seen in FIGS. 1 and 2,is provided for a gearwheel mechanism of a motor vehicle and serves toshift to and fro between two coaxial, different speed gears of thegearwheel mechanism. The dual clutch has a synchronization unitaccording to FIGS. 1 to 9 which, before a positive shifting operationbetween a gear mechanism shaft (working shaft; not shown) and one of thetwo speed gears, performs a synchronization of the rotational speeds ofthe gear mechanism shaft and the corresponding speed gear.

An annular sleeve carrier 2 is also fastened to the gear mechanism shaft(not shown) in a rotationally fixed and axially secured manner. Thespeed gears which are coaxial with respect to the gear mechanism shaftare mounted on the gear mechanism shaft in a rotationally movablemanner. In each case one clutch gear 3 is connected fixedly to eachspeed gear, that is to say both in a fixed manner so as to rotate withit and in an axially fixed manner. The two clutch gears 3 are arrangedon opposite axial end sides of the sleeve carrier 2 and in each case areat the same axial spacing from the sleeve carrier 2. In order tosynchronize the corresponding rotational speeds, each axial side isassigned a frictionally acting synchronizer clutch 5 in the form of amultiple disk clutch. Each synchronizer clutch has an axially fixedclutch ring (not denoted in greater detail) in the region of therespective clutch gear 3 and an axially movable synchronizer ring 4which bears directly against the sleeve carrier 2. Each multiple diskassembly is provided with a plurality of inner disks and with outerdisks which are arranged between them, the inner disks beingrotationally fixed to the respective clutch gear 3 and the outer disksbeing rotationally fixed to the adjacent synchronizer ring 4. Both theinner disks and the outer disks are arranged axially movably coaxiallywith respect to a rotational axis of the gear mechanism shaft andtherefore also with respect to a rotational axis of the dual clutch. Inorder to mount the inner disks, each clutch gear 3 has a hub regionwhich projects axially toward the sleeve carrier 2 and is provided withan axial external toothing system, on which the inner disks are held ina rotationally locking but axially displaceable manner. For therotationally fixed holding of the outer disks of each multiple diskassembly, each of the two synchronizer rings 4 has toothing sections 11which are provided with correspondingly designed, axial internaltoothing systems 13. In addition, the toothing sections 11 are providedwith axial external toothing systems 14 which are recessed axially andradially to the outside in a stepped manner with respect to the internaltoothing systems 13, the pitch circle diameters of which correspond tothe pitch circle diameter of axial external toothing systems of theclutch gears 3 and the pitches of which are designed identically withrespect to the axial external toothing system of the clutch gears 3.

In order for it to be possible to displace the synchronizer rings 4axially for a corresponding actuation of the left-hand or right-handmultiple disk clutch, a total of six pressure pieces 7 which are held inthe sleeve carrier 2 in a rotationally fixed and axially movable mannerare provided distributed uniformly over the circumference of the sleevecarrier. To this end, a total of six pressure piece cutouts 10 (FIGS. 6and 9) are provided in the sleeve carrier 2. Each pressure piece 7 has aball element 17 which is loaded by compression spring and interactspositively with an inside circumferential groove 8 of a selector sleeve6 which is held on the sleeve carrier 2 in a rotationally locking butaxially displaceable manner. For this rotationally locking drivingaction but axial displaceability of the selector sleeve 6 on the sleevecarrier 2, the sleeve carrier 2 is provided with an axial externaltoothing system (not denoted in greater detail), the pitch circlediameter and pitch of which correspond to the axial external toothingsystems of the clutch gears 3 and of the toothing sections 11 of thesynchronizer rings 4. In an annularly circumferential manner, theselector sleeve 6 has a complementary internal toothing system 15 whichis designed as an axial toothing system like the external toothingsystem of the sleeve carrier 2. An actuating linkage of the gearwheelmechanism acts on the outside of the selector sleeve in a way which isknown in principle and is therefore not shown in greater detail.

As can be seen using FIGS. 3 to 9, the sleeve carrier 2 is provided, ina manner which is distributed over its circumference, with a total ofsix axial cutouts 9, of which in each case three axial cutouts 9 areassigned to opposite axial end sides of the sleeve carrier 2. The ineach case three axial cutouts 9 of each axial end side of the sleevecarrier 2 are distributed uniformly over the circumference andaccordingly have circumferential angles of 120° with respect to oneanother. The other axial cutouts 9 on the opposite axial end side arearranged on the circumference of the sleeve carrier 2 offset by half thecircumference between two axial cutouts, with the result that theoverall six axial cutouts 9 are arranged distributed over thecircumference of the sleeve carrier 2 at circumferential angles of 60°in an alternating manner on the left-hand and right-hand side, inrelation to the illustration of the drawing, by in each case one axialcutout 9 which is open toward a left-hand end side being followed in thecircumferential direction by an axial cutout 9 of a right-hand end sideof the sleeve carrier 2 and in the following course in thecircumferential direction again by a left-hand axial cutout. Therespective pressure piece cutout 10 is provided centrally on half thecircumferential length of each axial cutout 9.

The axial cutouts 9 serve to axially receive the toothing sections 11 ofthe two synchronizer rings 4, one synchronizer ring 4 being assigned tothe left-hand axial end side and the other synchronizer ring 4 beingassigned to the right-hand axial end side of the sleeve carrier 2.Accordingly, each synchronizer ring 4 has three toothing sections 11distributed uniformly over its circumference. Each synchronizer ring 4is provided with a carrier ring 12, to the outer circumference of whichthe toothing sections 11 are fastened so as to project axially to thesame axial end side. In the exemplary embodiment which is shown, thetoothing sections 11 are welded fixedly to the outer circumference ofthe carrier ring 12. In other embodiments (not shown), it is provided toform the toothing sections 11 integrally on the carrier ring 12 or tofasten the toothing sections 11 to the carrier ring with the aid ofmechanical fastening means.

The length of the toothing sections 11 in the circumferential directionis somewhat smaller than the circumferential length of the axial cutouts9 of the sleeve carrier 2, as can be seen using FIGS. 3, 4 and 9. Thethickness, that is to say axial extent of the external toothing systems14 of the toothing sections 11 is smaller than an axial depth of theassociated cutouts.

After mounting of the synchronizer rings 4, the synchronizer ringstherefore do not project axially beyond the sleeve carrier 2 in theregion of their external toothing systems 14. The internal toothingsystems 13 which are offset radially to the inside and axially laterallycan project axially beyond the cutouts if this is required on account ofa specific refinement. The internal toothing system 15 of the selectorsleeve 6 is likewise provided with cutouts 16 at the level of the axialcutouts 9 and therefore at the level of the external toothing systems 14of the toothing sections 11 of the synchronizer rings 4, in order for itto be possible to achieve the desired synchronization and shiftingfunctions despite the synchronizer rings 4 which are integrated axiallyinto the sleeve carrier 2. In FIG. 8, the circumferential groove 8 onthe inside of the selector sleeve 6 can also be seen, into whichcircumferential groove 8 the ball elements 17 of the pressure pieces 7engage.

The function of the different elements of the dual clutch does notdiffer in principle from the function of known dual clutches. In theillustration according to FIGS. 1, 2 and 5, the selector sleeve 6 issituated in its neutral position, in which both multiple disk clutches 5are ventilated and the sleeve carrier 2 rotates with its gear mechanismshaft independently of the speed gears and the associated clutch gears3. As soon as the selector sleeve 6 is then displaced axially from saidneutral position, the circumferential groove 8 drives the correspondingpressure pieces 7 in the sleeve carrier 2 axially via the ball elements17, as a result of which they exert an axial pressure force on thecarrier ring 12 of the corresponding synchronizer ring 4. At the sametime, corresponding end sections of the internal toothing system 15 ofthe selector sleeve 6 which taper acutely in a wedge-shaped manner comeinto contact with corresponding end sides of the external toothingsystems 14 of the toothing sections 11 and press the latter positivelyinto an axially aligned orientation. At the same time, a frictionalconnection to the adjacent clutch gear 3 is built up via thecorresponding multiple disk assembly by the axial displacement of thesynchronizer ring 4. As soon as the rotational speeds of the clutch gear3 and of the sleeve carrier 2 are equalized via the correspondingmultiple disk clutch 5, the selector sleeve 6 is displaced completelyinto its shifting position, with the result that it engages axially overthe corresponding clutch gear 3 (see the illustration in FIG. 4). Theshifting operation is therefore ended. During this axial displacement ofthe selector sleeve 6, each ball segment 17 of the pressure pieces 10 ispressed out of the inner circumferential groove 8 of the selector sleeve6 counter to the pressure force of the inner compression spring. Arenewed return of the selector sleeve 6 into the neutral position ispossible by simple axial displacement, since the clutch gear 3, theassociated synchronizer ring 4 and the sleeve carrier are held by theselector sleeve 6 in a rotationally fixed manner and such that they arealigned axially with their toothing systems. Here, the pressure pieces 7are retracted again, by the ball elements 17 sliding into thecircumferential groove 8 again during a corresponding axial returnmovement of the selector sleeve and being moved back positively axiallyinto the neutral position.

1. A synchronization unit for a positive dual clutch, in particular fora gearwheel mechanism, having a sleeve carrier which is connectedaxially and fixedly to a working shaft so as to rotate with it, andhaving a selector sleeve which is fixed rotationally and can bedisplaced axially relative to the sleeve carrier, and having twofrictionally acting synchronizer clutches which are assigned to oppositeaxial sides of the sleeve carrier and in each case one clutch gear, eachsynchronizer clutch having a multiple disk assembly, and having aplurality of pressure pieces which are arranged distributed over thecircumference of the sleeve carrier and are mounted in an axiallyadjustable manner by way of the selector sleeve for loading one or theother synchronizer clutch, wherein sleeve-carrier-side synchronizerrings of the synchronizer clutch and the sleeve carrier have axiallyindented circumferential sections.
 2. The synchronization unit asclaimed in claim 1, wherein the sleeve carrier is provided with aplurality of axial cutouts which are arranged distributed over itscircumference and are open in an alternating manner toward opposite endsides of the sleeve carrier.
 3. The synchronization unit as claimed inclaim 1, wherein each synchronizer ring is provided with a number oftoothing sections which corresponds to the number of axial cutouts of anend side of the sleeve carrier, which toothing sections are fittedaxially and radially into the cutouts
 4. The synchronization unit asclaimed in claim 3, wherein the toothing sections are arranged in theassociated cutouts with play in the circumferential direction.
 5. Thesynchronization unit as claimed in claim 3, wherein the selector sleevehas an axial inner toothing system which is complementary with respectto the toothing sections and is recessed in sections in the region ofthe toothing sections of each synchronizer ring and at the radial levelof the cutouts of the sleeve carrier.
 6. The synchronization unit asclaimed in claim 5, wherein the recessed regions of the selector sleeveare made from opposite end sides in a complementary manner with respectto the cutouts of the sleeve carrier such that they alternate and aredistributed over the circumference.
 7. The synchronization unit asclaimed in claim 1, wherein both the sleeve carrier and the selectorsleeve which is arranged on the sleeve carrier in a rotationally fixedand axially movable manner have complementary axial toothing sectionswhich extend over the entire axial length of sleeve carrier and selectorsleeve, the axial toothing sections being provided, as viewed in thecircumferential direction, between the cutouts of the sleeve carrier andthe recessed regions of the internal toothing system of the selectorsleeve.
 8. The synchronization unit as claimed in claim 1, wherein thepressure pieces are arranged axially adjacently to the cutouts for thetoothing sections in the sleeve carrier.
 9. The synchronization unit asclaimed in claim 8, wherein the pressure pieces comprise ball elementswhich are loaded by compression spring and interact with an insidecircumferential groove arrangement of the selector sleeve, in order toensure axial displaceability of the pressure pieces during an axialmovement of the selector sleeve.